Transmitter circuit



Nov. '29, 1938. R. BRUCKNER TRANSMITTER CIRCUIT Filed NOV. 21, 1936 OUTPUT INVENTOR RICHARD 'BRUCKNER ATTORNEY Patented Nov. 29, 1938 UNITED STATES TRAN SMITTER CIRCUIT Richard Bruckner, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic m. b. H., Berlin, Germany, a corporation of Germany Application November 21, 1936, Serial No. 112,038

3 Claims.

In self excited transmitters it is known that a constant amplitude can be attained, for example, by detecting the produced high-frequency in a special tube, and the D. C. component of the detected oscillation produces a voltage drop through a high-ohmic resistor, which voltage drop exerts a regulating influence upon the grid of the transmitter tube. When the high-frequency amplitude increases, a negative potential is produced at the resistor which moves the working point of the transmitter tube into the negative region thereby decreasing the amplitude.

This regulation can, however, be employed only to a limited degree, since with the displacement of the working point into the negative region there increases the danger of interfering with the proper operation of the system.

In accordance with the invention this danger is overcome in that besides the said regulation, an additional load resistor which depends upon the amplitude is employed in parallel to the transmitter tube, and which increases when the amplitude decreases, removing thereby load from the transmitter circuit thus sustaining the oscillation.

The single figure of the drawing shows, by way of example only, a transmitter circuit having a vacuum tube arranged for self excitation at substantially constant amplitude, constructed in accordance with the principles of the present invention. This circuit includes an ordinary self excited oscillator transmitter tube V1 across whose output electrodes are arranged a pair of electron discharge devices V2 and G. The high frequency in the plate circuit is passed across the condenser C into the control tube V2 connected as anode rectifier, whereby it will be rectified and produces a voltage drop through the resistor R serving as grid bias for the transmitter tube.

Furthermore, an additional load branch is placed in parallel to the plate circuit of the transmitter tube, and which consists of a detector G and a voltage source B in series (or also in parallel) thereto, and a choke Dr closing the D. C. path. The detector bias B is so chosen that the positive peaks of the high-frequency produced by the transmitter tube, exceed normally the detector bias B. Then a small current flows and which represents a load for the transmitter tube. When the high-frequency amplitude decreases, the current in the detector decreases, and thereby the load decreases comparatively much more, since the load does not depend upon the entire high-frequency amplitude, but only upon the peaks exceeding the bias, and which make up only a fraction of the entire high-frequency amplitude. The load becomes a zero when the positive peaks of the high-frequency have dropped to the value of the bias B.

In Germany November 19, 1935 Only when using simultaneously the two features of the invention, namely, the amplitude regulation and the additional load resistor depending upon the amplitude, is it possible to operate with a high control potential and, therefore, to attain a wide control action. Since in this way, the working point of the transmitter tube is to a wide degree maintained at the same place independent of the outer influences, not only constancy of the amplitude, but also that of the frequency is assured, a condition which is of great importnace in the case of short waves. Moreover, the invention ofiers the advantage that the amplitude is independent of the wave length produced in the transmitter.

The present invention can be applied especially to control stages of remote controlled transmitters or of frequency multipliers in which a high degree of amplitude and frequency constancy is required.

I claim:

1. In combination, an electron discharge device oscillator having an anode, a cathode and a grid, a series circuit of a coil and a condenser between said grid and cathode, an oscillatory circuit including a coil coupled to said first coil connected between said anode and cathode, and a series circuit of condenser, an electron discharge device detector and a source of bias potential in the order named connected between 0 said anode and cathode, whereby only positive peaks of potential generated by said oscillator which exceed the bias of said source causes current to flow in said detector.

2. A system in accordance with claim 1 including an electron discharge device rectifier connected in shunt to said oscillator, said last device having a grid capacitively coupled to the anode of said oscillator, an anode resistively coupled to the junction of said first condenser and first coil, and a cathode coupled through a source of potential to the cathode of said oscillator.

3. A high frequency system for obtaining 0scillations of substantially constant frequency and amplitude, comprising an electron discharge device oscillator having input and output electrodes coupled together for self oscillation, a load in the form of a detector across said output electrodes for decreasing the amplitude thereof when said amplitude exceeds a mean value, and a multielectrode rectifier in parallel relation to said detector, said rectifier having grid and anode electrodes, said grid being coupled to the output electrode of said oscillator, and said anode being conductively coupled from a direct current standpoint to the input electrode of said oscillator to control the bias thereof, whereby the amplitude of oscillations is increased when said amplitude falls below said mean value.

RICHARD BRUCKNER. 

